Sedentary behavior is a major threat to the health of millions of Americans. The purpose of the proposed study is to test the ability of two behavioral change models to increase physical activity in a sedentary population. The participants in the study will be enrolled from a large inner-city general medical clinic which provides health care to a group of predominantly African-American, low socioeconomic status, sedentary workers. Participants will be randomly assigned to either a Control, a Patient-Provider, or a Patient-Peer condition. Participants in the Control condition will have access to a 78,000 square feet exercise facility with numerous options for exercise. Those in the Patient-Provider condition will have the same access to the exercise facility and will also receive face-to-face, systematic, encouragement from trained medical interventionists. Those in the Patient-Peer condition will have the same access to the exercise facility and will also receive face-to-face, systematic, encouragement from trained peer interventionists. Changes in exercise behavior will be documented by monitoring use of the facility and by self-reported physical activity levels. Changes in fitness levels will be assessed by regular testing during 12 months of active intervention and 18 months of follow-up monitoring. Behavior change experts, exercise intervention specialists, and health-care professionals from the University of Tennessee Health Sciences Center and The Church Health Center of Memphis, a non-academic, church-based health organization, will collaborate on the study.